CDMA2000 is a third-generation (3G) wireless communications standard that uses Code Division Multiple Access (CDMA) to facilitate wireless communications between CDMA base stations and mobile devices. Variants of CDMA2000 include CDMA2000 1x, which provides both voice and data services over a standard CDMA channel, and CDMA2000 Evolution Data-Optimized (1xEV-DO) which is optimized for High Data Rate (HDR) capability. CDMA2000 1xEV-DO Revision B defines a multi-carrier system providing peak transmission rates of 73.5 Mbps in the forward link and 27 Mbps in the reverse link by aggregating multiple 1.25 MHz carrier within 20 MHz of bandwidth. Current versions of the CDMA2000 standards are published and approved by the Telecommunications Industry Association and the International Telecommunication Union.
FIG. 1 illustrates exemplary forward link channel structures for use in a DO multi-carrier system. As shown, base transceiver 100 provides three CDMA2000 1xEV-DO carriers, which are optimized for high speed data communications. The three depicted CDMA2000 1xEV-DO carriers include forward link channels 110, 120 and 130, respectively. Each forward link channel 110, 120 and 130 includes time slots allocated for pilot channels for system acquisition, and control channels for providing control information to mobile stations. In operation, the mobile station 140 separately acquires the pilot and control channels for each 1xEV-DO carrier to set up wireless communications on the respective carrier.
The base transceiver 100 allocates wireless resources, such as time slots on the 1xEV-DO carriers, to the mobile station 140 based on the mobile user's Quality of Service (QoS) characteristics. A mobile station with high QoS characteristics may be given priority over other mobile stations to ensure data communications to the mobile station are delivered at a high data rate, for example by assigning additional time slots on forward link channels 110, 120 and 130. In addition, subscribers in good radio frequency (RF) conditions are served first under current scheduling protocols.
However, there is currently no way to service a high QoS subscriber who happens to be in a bad RF environment without materially decreasing sector throughput for the servicing base transceiver system (e.g., base transceiver 100). As such, there is a need for a system and method for improving sector throughput in a broadband data-optimized multi-carrier environment.